Rock drill



' construction of the rock drill according to y Y y y pivot comprisingal semi-spherical recess I17 the drill, `and finally toobtain PatentedFeb. 8,1927.'

` narran srarss TAKAsUxE NAKAYAMA, for' osAxA, JAPAN, Assienon To sumarrIARAfANn KaisHA 1v'AKAYAMA ricevo-siro,Y oil osAKaJArAN.

i i 'nausea mim i ROCK DRILL.'

Application mea March s, 192e`,`seria1 No. 93,244,-ana in Japan Aprirzo,`1925.`

This invention relates vto `improvements in rock drills driven byelectric motors. Ity consists of a shaft-'Whichis a` sliding fit in therotor; one end of theV shaft being pro` vided with a toothed Wheelgeared to another toothed Wheel, which in turn, drives `the drill, Whilethe other end of thev shaft is connected by a ball joint with aspherical pivot locatedeccentrically onV a table which can be turned atWill. V

The object of this invention is, 1 to strike A the drill once perrevolution of the rotor While the latter rotates the former, 2 toVfacilitate the control of the strikingforce of La c ompact krock drillwith` a high efficiency: V

The accompanying drawings show the this invention, in Which v`F ig. 1 isa sectional elevation on the Centre line 'of the rock drill. A' j 2 is aplan of the spindle with the toothed Wheel which drives t-he drill,showing a trapezoidalrecess of the claw clutch. Fig. 3 is a sectionalelevation of the'rear part of the rock drill with the table in such .v

a position that the centre of the spherical pivot is situated on theaxial line of the rotor shaft.

In Fig. 1, 1 is the cylindrical Vframe of the rock drill, which can -bemoved back VWards or forwards by the screw With handle 29, and 2 is thestator of the electric motor provided inside the frame, While 3 is thev`rotor; its sheet-:iron corebeing mounted on sleeve 4. A short pipe 5is extended from, andf'orms part of the sleeve, and is mounted so thatit can rotate in ball bearing 6.

1A anged pipe 7 that can rotate freely in ball bearing 9provided withkeys '8 which extend into the adjacent end of the sleeve and fit intokeyways .on shaft 1(7). This shaft extends through thel sleeve 4 and thepipe 5, and rotates With the rotor by means of the keys S, but can slideaxially along the sleeve. An elongated toothed Wheel 11 is provided atone end of the shaft While ball joint 12 is provided at the other end.The wheel 11 gears with anotherI toothed Wheel 13 which is looselyfitted on stepped spindle 14,"on Which is Wheel 26 driving Wheel 27Which carries a chuck for the drill. The boss `of the Wheel 13 hastwo or-three trape# zoidal projections; which fit into the correspondingrecesses on thershoulder of the stepped spindle and forms a clavi7clutcl1.- Each side'of the projection and the recess is properlyinclined tothe Aaxial line as shown in Fig. 2. In a central Vrecess inthe boss of the wheel is provided Withv a spring 15, and a nut 25screwed on the `end ofthe spindle 14 nia-kes the spring press the bossinto the clutch member of thespindle, and should the drill not rotatedue to anyabnormal resistance or accident, theboss is automaticallyforced out-Wards due to `the inclination of the recess and projectionofl the claw clutch compressing the spring', andy disengaging the clutch4so 'that' the Wheelv rotates freely onv the spindle.

At the rear end of the frame is a table 16 eccentrically fitted Whichcan be rotated at Will by means ofk ahandle 28. j A spherical and aSpherical membefls is eccentrica@ provided on the table,fand` a rod-2Owith a ball ofthe ball joint is held inthe sphericalj` member, and a.ring 19 is fitted in the member With a pin. lVashers 21 and 22 are"8 nSince the spherical pvot connected by the y ball joint to the rotorshaft is situated ec '.centrically to the axis of the shaft, onerevolution of the shaft gives itself an axial movement, therefore thedrill, Which is Vheld in the chuck in contact directly or indirectlyWith the head of the rotor shaft, is struck the same number of times asthe rotor rotates. YWhen the rotor shaft is at each extreme end of itsaxial movements, the spring in the spherical pivot is compressed byeither ofthe Washers 21 and 22, so that the shock Which Wouldbe given tothe rotor `shaft at the extreme ends of its movements is moderated.

When the table is turned half a revolution from the position shown inFig. 1, the centre of the spherical pivot and the axis of the v rotorshaft are coincident, so thatthe revolution'of the shaftidoes not movein axial direction, but only rotates the head of the rod in thespherical pivot. In other Words the length of a stroke of the shaftisthe minimum or zero When the same is in the position shovvn in Fig.A 3.Placing the spherical pivot Y in any position betvveen these tWo eXtremei points, any required length of stroke of the Yshaft can be obtained2so that the intensity of the blow of, Y the drill can be easilyadjusted.

In case the drill can not be turned mounted on a rotatable table on theframer and connected by a ball joint to the othery end of the shaft. Y ii 2. AV rock drill comprising` an electricmo'- tor in a frame, the shaftof the motor having a sliding fit in the rotor, a toothed Wheel providedon one end of the shaft tor driving a drill, and a spherical pivoteccentricallyY mounted on a rotatable table on theframe and connected bya ball joint to the other end of the shaft, the spherical pivot beingprovided with a helical spring-and a rodv With a ball for the ball jointWithin the spherical member so` as to moderate the Vshock Which Would beproduced atthe eX- treme ends of axial movements of the rod vby thecompression of the spring.

3. A rock drill comprising an electric modue Vto an abnormal resistanceor any such accitor in a frame, the shaft of the motor having a slidingfit in the rotor, a spherical pivot eccentrically mounted on a rotatabletable` on the frame and connected by a ball joint to the other endv ofthe shaft, atoothedv Wheel provided on an end of the shaft to drive adrill through intermediate gears,

and a jaw clutch, which is engaged by the pressure of a spring butautomatically dis-V engages the connection of the intermediate gearsWhen an abnormal resistance is en-` countered by the drill. y

' el. VA rock drill comprising an electric motor in a Jframe, the shaftofthe motor having a sliding iit in the rotor, a toothed Wheel providedon an end of the shaft to drive a drill through intermediate gearsincluding a jaw clutch with trapezoidal recesses andV projections and aspring, and a spherical pivot eccentrically mounted on a rotatableltable on the trame and connected by a ball joint with the other end ofVthe shaft, said spherical pivot being provided With a helical spring anday rod with a ball of the ball joint Within the spherical member, forthe purpose of striking the drill onceper revolution of the shaft,of-facilitating the control ot the striking intensity` of the drill,andV for automaticallydisengaging the connection of the driving gearsforr the drill.

when an abnormal resistance is encountered. Vby the drill.

In testimony whereof' I hereunto aiiiX my signature.

TAKASUKE NAKAYAMA.

